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Inheritance of chromosomal length polymorphisms in the ascomycete Leptosphaeria maculans
1Plant Cell Biology Research Centre, School of Botany, University of Melbourne, Parkville, VIC, Australia.
Abstract:
Pulsed field gel electrophoresis experiments show that chromosomal length polymorphisms are produced during meiosis in the ascomycetous plant pathogen Leptosphaeria maculans. Homologues in tetrads of L. maculans were identified on the basis of their binding to chromosome-specific probes that included beta-tubulin, nitrate reductase, 18S ribosomal DNA and two Random Amplified Polymorphic DNA (RAPD) markers. Changes in size of homologues were followed during meiosis. Significant karyotype variation was evident due to the random assortment of parental homologues of different sizes. In most cases, the progeny had the same-sized homologues as the parents; however, in some instances novel-sized homologues were detected that varied in size from those of the parents by up to 50 kb. Our results are consistent with the hypothesis that these novel chromosomal length polymorphisms are produced by reciprocal recombination between parental homologous chromosomes of unequal sizes.
Insights
Chromosomal length polymorphisms arise during meiosis in Leptosphaeria maculans. These variations, potentially from unequal recombination, contribute to karyotype diversity in this plant pathogen.
Area of Science:
- Genetics
- Molecular Biology
- Plant Pathology
Background:
- Leptosphaeria maculans is an ascomycetous plant pathogen.
- Understanding chromosomal dynamics during meiosis is crucial for pathogen evolution.
Purpose of the Study:
- To investigate chromosomal length polymorphisms during meiosis in Leptosphaeria maculans.
- To identify the mechanisms generating karyotype variation in this species.
Main Methods:
- Pulsed field gel electrophoresis (PFGE) was employed to analyze chromosomal DNA.
- Chromosome-specific probes, including beta-tubulin, nitrate reductase, 18S ribosomal DNA, and Random Amplified Polymorphic DNA (RAPD) markers, were used for homologue identification.
- Changes in homologue sizes were tracked through meiosis.
Main Results:
- Chromosomal length polymorphisms were observed during meiosis in L. maculans.
- Karyotype variation resulted from the random assortment of parental homologues with differing sizes.
- Novel-sized homologues, varying up to 50 kb from parental sizes, were detected in progeny.
Conclusions:
- The observed novel chromosomal length polymorphisms are likely generated by reciprocal recombination between homologous chromosomes of unequal sizes.
- This mechanism contributes to genetic diversity and karyotype variation in Leptosphaeria maculans.